Means for automatically controlling the supply of liquid fuel to a prime mover



Oct. 5, 1948. E. A. WATSON ET AL 2,450,535

MEANS FOR AUTOMATICALLY CONTROLLING THE SUPPLY OF LIQUID FUEL TO A PRIME MOVER Filed Feb. 7, 1944 i PM dl 11% V )2 I z' 9 K if I 12 z I HUI/l! k I /////1 1 44F v 11 k w 1 Q 10 F L\ 1 27 .IZY/UCWZS l' d kTarl/ozz/ Patented st. 5, l9

UNITED A,

STATES PATENT OFFICE- MEANS FOR AUTOMATICALLY CONTROL- LING THE SUPPLY OF LIQUID FUEL TO A I PRIME MOVER Ernest Ansley Watson, Gibbet Hill, Coventry, and

Richard Joseph Ifleld, Ealing, London, England, assignors to Joseph Lucas Limited, Birmingham, England Application February 7, 1944, Serial No. 521,470 In Great Britain December 16, 1942 by a blower. The object of the invention is to provide improved means for controlling the rate of fuel supply in'a manner which is correlated with the pressure of the air delivered by the blower.

In the accompanying sheet of explanatory drawings Figure l is a diagrammatic sectional side elevation of a variable-output fuel pump embodying the invention.

Figure 2 is a sectional view illustrating a modified form of the invention.

The liquid fuel pump shown in Figure 1 comprises a rotary body part a arranged in a casing 22 and having formed around its axis a plurality of bores as c in each of which is arranged a reciprocatory plunger as d. The body part a is adapted t0 be driven in any convenient manner by the prime mover (not shown) to be supplied with liquid fuel from the pump. During rotation of the body part a the plungers d are moved in one direction by an angularly movable swash plate e and in the opposite direction by springs as the latter being situated within the bores c, and serving to hold an end face of the body part in contact with a flat seating g in the casing 12..

To enable the pump above described to be governed in response to variations in speed, the body part a is adapted to serve as a centrifugal pump. Thus, the body part a is formed with an axial bore m which at one end communicates with the inlet 1 through another port 11. in theseating g, and at the other end communicates with a plurality of radial passages as min the body part. Liquid fuel from the inlet 1 flows through the bore 112 and is expelled by centrifugal action through the radial passages 0 into the interior of the casing b around the body part a. In one end of the pump casing b .is formed a cylinder 1) having closed ends. Within the cylinder p is arranged a piston q loaded by a spring 1', and extending from one side of this piston and through a bore in the casing b at the inner end of the cylinder is a rod s connected to the swash plate e. The inner portion of the cylinder p, that is the portion at the piston-rod side of the piston q, is in free communication with the outlet is through a passage lin the casing b, and this portion of the cylinder also communicates with the other or outer portion of the cylinder (which contains the spring 1) through a restricted passage t. The outer end of the cylinder p is provided with a small vent u which at its outer end forms a seating for a closure member 0 on one end of a lever w, the latter being pivoted at a position between its ends on the outer end of the cylinder, and being loaded by a spring a: which tends to hold the closure member on its seating. The lever to is contained in a chamber 2/ formed on or secured to the adjacent end of the casing b, and this chamber communicates with' the pump inlet 5 through a passage 2. The outer side of the chamber 11 is bounded by a controlling diaphragm 2 having at its centre an abutment 3 which is adapted to bear on the end of the lever w remote from the closure member '0. At the outer side of and bounded in part by the diaphragm 2 is another chamber d, this latter chamber being in communication with the above-mentioned centriiugal pump through a passage 6 in the casing 12. Also the diaphragm 2 is loaded by a spring 3 connected to an adjusting member l, the latter being operable in any convenient manner. by an attendant to vary the effect of the spring.

Assuming the swash plate e to be in the posi tion of maximum obliquity, that is to say the position in which the pump gives its maximum output, the swash plate will remain in this position so long as the pressure in the chamber 6 (and thus acting on the controlling diaphragm Z) is below some predetermined amount. In this condition the vent closure member 1; is in its closed position and the'liquid pressures at the two sides of the piston q are equal. But when the pressure acting on the diaphragm 2 exceeds the predetermined amount the diaphragm will move the closure member 1 oil its seating. The liquid pressure in the outer portion of the cylinder p will now fall and the piston q will be moved by the .fluid pressure in the inner portion of the cylinder against the action of the spring 1', s0 moving the swash plate e in the direction for reducing the .pump output until a new condition of equilibrium is reached.

From the foregoing it will be seen that as the position of the swash plate e is dependent on the pressure of the liquid in the chamber 4, and as assume 3 let it, an automatically variable orifice 8 through which the liquid fuel is caused to fiow. This orifice s is formed by a fixed annulus it in the chamber I, and a coaxial tapered plug ii slidable of the plug ii is made to any appropriate shape such as will cause the area of the orifice to change with the axial movement of the plug in a predetermined manner. Movement of the plug ll relatively to the annulus ID in' opposition to the spring it depends on difference of fluid pressure at the two sides of the orifice I and consequently on the rate of flow of liquid through the orifice, the area of the orifice being automatically varied by the plug with variation in the rate of flow.

To regulate the rate of flow of liquid through the orifice I we employ any convenient means which is responsive to the said difference of liquid pressure and the blower-air pressure. As shown in Figure 1 such means consists of a diaphragm II to which one endof the stem i2 is attached,

and which serves to divide a chamber in the pump casing b into two compartments II, It. The compartment I8 is open to the atmosphere or evacuated through an opening is, and the compartment I! is adapted to receive air through a connection 24 from 'a blower 2!, this latter being driven by, and serving to supply air required for combustion of the fuel to the prime mover.. The stem I2 is adapted to control the flow of liquid fuel to the chamber 8, and for this purpose in the example shown is provided at the end remote from the diaphragm ID with a valve IS. The latter serves by controlling a vent passage IT in the outer end of the cylinder p to vary the output of the pump in response to axial movement of the stem l2.

When the pump above described is in action the areaof the orifice I depends automatically on the rate of fiow of liquid through the orifice,

variation in the rate of fiow being accompanied by a corresponding change in the position of the plug ii. For a given rate of flow there will be a corresponding pressure difference between the two sides of the annulus ill. 80 ions as this pressure difference is balanced by the blower-air pressure acting on the diaphragm II, the rate of flow of liquid through the orifice 0 will remain constant. Variation of blower-air premure or of liquid how will upset the balance, and cause the stem If to effect an appropriate adJustment of the pump regulating valve ii.

In the modification shown in Figure 2, we employ an annulus I0 which is slidabie in a cylindrical chamber 8. and which is formed by one end of a sleeve 26 in the chamber, the other end of the sleeve being open and arranged to abut against an apertured disc 21 through which liquid can flow. In association with the annulus I0 is arranged a co-axial stem II on which is formed or secured a tapered plug ill. The plug ll and annulus I0 are loaded by a helical spring I3 whose ends abut respectively against a collar il on the stem I2 and against the annulus. Also we employ a pair of similar corrugated metal capsules I0 20 the interior of one (Il of which is adapted to receive air through a connection from the outlet of this pump flows through an 4 to the atmosphere through an aperture il or is charged with the liquid fuel at reservoir pressure. and being interconnected at their adjacent ends. Between and in contact with one of the adjacent ends of the capsules I0 20 is arranged one arm of a three-armed lever 22 One of the other arms of the lever 22 abuts against one end of the plug stem I2 through the medium of a thrust piece 23 and the remaining arm carries a valve I0 which serves by controlling a vent passage I! to control the output of a liquid fuel pump as in the example previously described. Fuel inlet 20 and the perforated disc 21 to the interior of the sleeve 20 and thence through the orifice formed by the annulus l0 and plug Il to the outlet it. As in the previously described example, the area of the orifice 8 depends automatically on the rate of flow of liquid through the orifice. variation in the rate of fiow being accompanied by a corresponding change in the position of the plug il 80 long as the difference of fluid pressure at the two sides of the orifice s is balanced by the blower-air pressure acting on the stem I2 through the lever 22, the rate of fiow of liquid through the orifice will remain constant, but variation of blower-air pressure or liquid flow will upset this balance and cause the stem to effect an appropriate adjustment of the valve I! through the lever. The chamber fl is provided with an outlet which at its inner end is provided with a filter il and which is adapted to communicate with a reservoir (not shown) connected to the pump inlet.

} The invention is not. however, limited to the examples above described. as details may be varied without departing from the essential features of the invention. Thus, instead of being used to actuate a valve, the stem in either of the examples above described may be adapted to actuate any other regulating device in the fuel supply system. By utilizing the pressure difference at the opposite sides of an automatically variable orifice through which the liquid fuel passes, and the pressure of the blower-air, we are able to correlate the supply -of liquid fuel and air to a combustion chamber in a very simple and satisfactory manner.

Having thus described our invention, what we doclaim as new and desire to secure by Letters Patent isz.

1. Means for automatically controlling the sup- 7 ply of liquid fuel from a pump to a prime mover 24 from the blower and that of the other is evacuated, these capsules being coaxially having associated with it a blower for supplying the air required for combustion of the fuel, comprising the combination of a chamber through which the liquid fuel can fiow, from the pump to the prime mover. an annulus slidably mounted in the chamber, a tapered plug arranged in the chamber coaxially with the annulus and formingwith the latter a variable orifice for controlling the flow of fuel through the chamber, the annulus and plug being such that their relative positions and consequently the area of the orifice are dependent on the difference of fluid pressure at the opposite sides of the orifice. an axially movable stem on which the plug is provided. a loading spring associated with both the annulus and plug. a lever adapted to be moved by and to impart movement to the stem, means for actuating the lever in response to blower-air pressure, and means operable by the lever for controlling the flow of fuel to the said chamber.

2. Means for automatically controlling the supl ply of liquid fuel from a pump to a prime mover having associated with it a blower forsupplying the air required for combustion'of the fuel, comprising the combination of a chamber through which the liquid fuel can flow from the pump to the prime mover, a pair of relatively movable coaxial parts forming in the chamber a variable orifice for controlling the flow of fuel through the chamber, the said parts being such thattheir relative positions and consequently the area of the orifice are dependent on the difference of fluid pressure at the opposite sides of the orifice, and means responsive to both this difference of pressure and the blower-air pressure for con-' trolling the supply of fuel to the chamber.

3. Means for automatically controlling the supply of liquid fuel from a pump to a prime mover having associated with it a blower for supplying the air required for combustion of the fuel, comprising the combination of a chamber through which the liquid fuel can flow from the pump to the prime mover, a fixed annulus arranged in the chamber, a tapered plug arranged in the cham-- ber coaxially with the annulus and forming with the latter a variable orifice for controlling the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,004,869 Hogg June 11, 1935 2,082,397 Hiscock June 1, 1937 2,222,919 Trapp Nov. 26, 1940 2,273,670 Udale Feb. 17, 1942 Udale July 28, 1942 

